Die mechanism for extruding compressed powder rods



Oct. 27, 1953 2,656,743

DIE MECHANISM FOR EXTRUDING coMPREssEn POWDER Rous E. K. LEAVENWRTH 5Sheets-Sheet 1 mea Fgb. 2s. 1951 Qct. 27, 1953 E. K. LEAvl-:NwoRTH2,656,743

DIE MECHANISM FOR EXTRUDING COMPRESSED POWDER RODS Filed Feb. 25. 1951 5Sheets-Sheet 2 [Tix Oct. 27, 1953 E. K. LEAvENwoRTH 2,656,743

DIE MECHANISM FOR bFx'rRumNc; rCOMPRESSE; POWDER Rous Filed Feb. .25.1951 5 Sheets-Sheet 3 ltr j I BY l l Oct. 27, 1953 E. K. LEAvENwoRTHDIE!v MECHANISM FOR EXTRUDING COMPRESSED POWDER RODS Filed Feb. 2S. 19515 Sheets-Smet',- 4

IN1/mmm Oct. 27, 1953 E. K. LEAVENWORTH 2,556.3'43

DIE'MECHANISM FOR EXTRUDING coMPREssED POWDER Rous ff JNVENTOR BY APatented Oct. 27, 1953 DIE MECHANISM FOR EXTRUDING COMPRESSED POWDERRODS Edgar K. Leavenworth, Birmingham, Mich., as-

signor to Climax Molybdenum Company, New York, N. Y., a corporation ofDelaware Application February 23, 1951, Serial No. 212,434

6 Claims.

This invention relates to die mechanisms for extruding compressed powderrods, and more particularly to mechanisms for forming a continuous rodof compressed powdered metal which is to be sintered prior to melting inan electric furnace.

The die mechanism which is the subject of the present invention is animprovement over that described in applicants copending application No.787,797, filed November` 24, 1947. In that application, an extrusion dieis disclosed having a reciprocating ram or plunger at one end whichpacks small incremental portions of the powdered material into the dieand compresses them at a predetermined consistency. The die is ofconstant cross-sectional area and is of such a length that thefrictional force oi the powdered metal against the walls of the die isalways sufficient to prevent axial movement of the rod due to the axialforce of the ram. The die is further provided with split portions whichare normally held against radial expansion, but which by an arrangementof a cone and springs are released for radial movement upon theattainment of a predetermined axial force, thus reducing the frictionalforce of the rod in the die suiliciently to allow axial movement of therod.

This mechanism presents inherent disadvantages which it is the object ofthe present invention to overcome. The springs which are used tocounteract the axial force of the ram are very cumbersome and laboriousto load. The die is required to have an axial motion, and bearingproblems result due to excessive loads on the cone. Furthermore, thesprings and cone operate as a friction brake when the compressed rod ismoved through the die, thus causing excessive die wear and wasted power.

It is an object of this invention to eliminate these disadvantages andto provide an improved die mechanism which is extremely flexible in itsoperation and in which the labor involved in replacing or readjustingthe parts is greatly reduced. In particular, it is an object toeliminate the spring arrangement and the attendant vertical motion ofthe die and compressed rod which is required to operate the cone andsprings in the previous structure, substituting instead a mechanismwhich normally exerts a positive force on the split die portions toprevent their radial expansion, together with tripping means forautomatically releasing this force when the axial force exerted by ramreaches a predetermined value. In association with this object, it iswithin the contemplation of this invention to provide a hydraulicmechanism in the form of a cylinder and piston for exerting the radialclamping forces on the die, and in which the hydraulic pressure in theram cylinder is used to trigger the release of pressure in the diecylinder, the pressure at which this triggering takes place beingadjustable by the operator.

It is a further object to provide an improved hydraulic system for anextrusion die mechanism of the above character, which is fully automaticin its operation and which includes means for varying the die cylinderreleasing point without affecting the eiiiciency or speed of the system`Other objects, features, and advantages of the present invention willbecome apparent from the subsequent description taken in conjunctionwith the accompanying drawings.

In the drawings:

Figure l is a side elevational view of the upper portion of an electricfurnace installation, showing the location of the die mechanism and itsassociated subassemblies.

Figure 2 is a plan cross-sectional View taken along the line 2-2 of Fig.l and showing the feeding troughs and the die mechanism.

Figure 3 is a cross-sectional View in elevation taken along the line 3-3of Fig. 2 and showing the die piston and cylinder as well as otherelements of the die.

Figure 4 is a fragmentary cross-sectional view taken along the line 4-4of Fig. 1 and showing the guide for the ram.

Figure 5 is a plan cross-sectional view taken along the line 5-5 of Fig.3 and showing the 1ocation of the die tension bolts.

Figure 6 is a front elevational View, partly in cross-section along theline 6 5 of Fig. 3 and showing the construction of the entering portionof the die elements.

Figure 7 is a plan cross-sectional view taken along the line 1--1 ofFig. 3 and showing the construction of the die segments and the diecollar.

Figure 8 is a plan cross-sectional View taken along the line 8-8 of Fig.3 and showing the die segment clamping blocks; and

Figure 9 is a schematic view of a preferred hydraulic system forcarrying out the principles of operation of this invention.

The principles of this invention are shown as enoodied in a device forproducing a continuous rod of sintered metal which is fed to theCrucible or mold of an electric furnace for melting into an ingot orother object. It will be understood 3 however that these principles mayas well be applied to other devices and installations where a continuousrod of compressed powder is desired to be formed. In the illustratedembodiment, after the rod leaves the die in its compressed form itpasses through a series of electrodes (not shown) where. it is subjectedto an electric current which heats the compressed particles suflicientlyto sinter them together, thus permitting the rod to continue downwardlytoward the furnace and still have sufficient strength to support its ownweight. It is of course important to the sintering operation that thedensity of the material in the rod before sintering have as littlevariation as possible, so that a uniform electric current will notproduce over-sintering in some portions of the rod and under-sinteringin others. For this purpose, it is necessary that the amount of powderthat forms each increment of the rod be held uniform within reasonablelimits, and that the compression Apressure for each increment besubstantially the same.

To carry out these purposes, the present invention provides a diemechanism `generally indicated at vII and a ram generally indicated atI2 which reciprocates within the upper or entering portion of the dieand upon each reciprocation packs an incremental amount of powderedmetal which is fed from a trough I3. Since the mechanism is shown asused in conjunctionwith an electric furnace, the entire assembly isenclosed bya housing I4 which is evacuated through a conduit I5 and iscooled by coils I6. The 'trough I3 may be of Ithe conventional vibratorytype, being supported at its outer end by vibratory spring I1, and isfed from `ahopper I8 mounted above the outer end. The inner end ofhopper I3 is forked, as shown in Fig. 2, and leads to both outer ends ofan elongated funnel I9 surrounding the ram I2 and surmounting the dieII. A vibrator 23 may be mounted on the funnel to insure a constant owof powder. The die itself is preferably suspended by means of aplurality of posts 2I, the lower ends of which hold Aa bedplate 22 uponwhich the die lis mounted. The ram lI2 is disposed between these postsand comprises a piston 23 extending downwardly ,from vthe ram cylinder'i9 (shown schematically in Fig. 9) and connected by a split element 24to the ram proper, -thus facilitating removal kof the parts. As shown inFigs. l and 4, a double armed guide member .25 having oppositelydisposed forked ends 26 is secured at the upper end of the ram I2 andslides between two diagonally opposite posts 2|, thus preventing lateralbuckling movement of the ram and increasing its columnar strength.

At the top of its stroke, as shown by the dotdash lines in Fig. 3, thereduced portion at the lower end of the ram is disposed within thefunnel I9, and the head member 21 is above the upper end of die II. Whenin this position, powdered `metal will be permitted to flow intoentering end of the die and when the ram is lowered, the head member 21will compress the powder into the die, the final position of the headmember being a snug fit within the die as shown Yin solid -lines in Fig.3.

The die into which the powdered metal is forced by the ram is shown inthe illustrated embodiment as having a constant cross-section ofvhexagonal shape. However, it willbe understood that othercross-sectional shapes could be'used for the die within the principlesof the invention. As is best seen in Figs. 7 and 8, the 'die comprisessix elongated segments 28, 29, 3i, 32, 33 and 34 which together form anelongated rod-forming passageway of hexagonal cross-section. Inparticular, each of these segments has an inner face 35, and outer face36 and sides 37 which have matching inwardly inclined portions 38. Theseinwardly inclined portions are normally in fiush relation so that theinner surfaces 35 form the hexagonal passageway. Adjacent the upper endof each of these die segments is an outwardly facing transverse slot 39,and a pair of supporting plates 4I and 42 vare engaged in these slotsand support the die segments against axial movement, a certain amount ofplay being permitted between the plates and die in a radial direction,as shown in Fig. 3. Plates 4I and 42 rest upon the upper surfaces ofthedie segment clamping blocks 43 and 44, which surround the major portionof the die segments below the slots 39 in a manner hereinafter describedin detail. A collar 45 is disposed 1 around the die segments aboveplates 4I and 42,

and extends `to the upper ends of these die segments. The lpurpose ofVcollar 45 is vto positively prevent at all times any relative movementfof the upper portion of the die segments, thus `'crea-ting in eifect anlimmovable die at this entering portion. For this purpose, the collar 45preferably has a press `iit with the outer vfaces 35 -of the `-diesegments, so that the matching surfaces 38 of the segments are in tightrelation to prevent any powder working in between the segments. Theheight of collar 45 and thus of the solid portion of the die is suchthat the cavity found inside the die and above the open splits will`contain the maximum amount of loose powder which is to vbe compressedfor any one increment.

The die segment supporting plates 4! and -42 are secured to the diesegment clamping block 44 by means of bolts 46, but are movable withrelation to block 43. The blocks 43 and 44 extend downwardly from thesupporting plates 4i and 42 :substantially along the remaining length ofthe die segments, and are supported by the bedplate 22. The bedplate hasa clearance aperture 47 into which the lower ends of the die segmentsextend, and which allows the Vdownward passage of the compressedpowdered rod from the die. Blocks 43 and 4E each have an interiorclampingsurface 48 of such configuration as to simultaneously surround.three of the die segments so as to prevent their routward radialmovement. In particular, block 44 engages die segments 28, 29 and 3Iwhile block 43 engages the remaining die segments 32, 33 and 34. Theblocks are capable khowever of a releasing movement (block 43 to theleft and block 44 to the right relative to the die strips as shown inFigs. 3 and '8) so as to relieve their engaging pressure on theirrespective die segments, thusreducing the frictional forces on the rod.

To accomplish this action, a die cylinder 49 and a die piston 5I areprovided adjacent the blocks and are operatively connected thereto. Asis Ybest seen in Figs. 3 and 8, the die cylinder 49 is in spacedrelation with block 43 and is so disposed that the cylinder axis isperpendicular to the axis of the die passageway. In the illustratedembodiment, the diameter of cylinder 49 is such vthat it extendssubstantially the entire length of the die, the lower end of thecylinder side wall being adjacent but not supported by bedplate 22. Itwill be understood, however that the relative proportions of the diecylinder are not critical but may be varied to suit the installation.The louter end wall 52 of the die cylinder is 'iiared slightlyoutwardly, and the central portion thereof is -provided with a guideway53 for slidably supporting an extension 54 of the die piston 5|. Theinner end of the die cylinder is provided with a head 55 secured theretoby cap screws, and this head has a central bearing aperture 56 whichslidably supports inner extension 51 of the die piston 5|. Extension 51is of substantially greater diameter than extension 5,4, and has an endface 58 of relatively large area which engages the outer flat face 59 ofblock 43. An hydraulic pressure connection 6| leads to the outer endwall 52 of the die cylinder, and is connected by axial port 62 andradial ports 63 in extension 54 to the pressure chamber 84 of the diecylinder. Sealing rings 65 and 66 may be provided on the die piston andon extension 51 respectively to prevent oil leakage. The opposite sideof die piston 5| is preferably connected by a conduit 61 to a source ofvacuum, so that oil leaking in to the chamber 88 will not contaminatethe vacuum surrounding the entire pressing mechanism.

While as stated previously die piston 5| is operatively engageable, bymeans of mating faces 58 and 59, with die segment clamping block 43, thedie cylinder 49 is connected to the die segment retaining block 44. Forthis purpose, a plurality of tension bolts 69 are provided, and thesebolts are connected at one end to the die cylinder and at their oppositeends to a bearing plate 1|. As is best seen in Fig. 6, the side wall ofthe die cylinder is enlarged at four circumferentially spaced points inorder to accommodate these bolts, and the bolts in turn are disposedinwardly from the supporting posts 2 I. The tension bolts 89 pass freelythrough die cylinder head 55, and tubular spacers 12 surround theintermediate portions of the bolts between head 55 and bearing plate 1l.This bearing plate has an inner face 13 which is engageable with theouter face 14 of die segment clamping block 44. Bearing plate 1| alsorests upon bedplate 22 and is connected thereto by cap screws 15.Clamping block 44 also is supported by bedplate 22 although not fastenedthereto, and retaining block 43, which as will later be described movesrelative to the bedplate, is supported thereby through an intermediatewear plate 16. The lost-motion connection of tension bolts 59 to diecylinder 49 and to bearing plate 1| is by means of outer nuts 11, whichpermit only a tensile stress to be placed in the bolts. A pair of legs18 are also provided on bedplate 22 to support the weight of diecylinder 49 which however is not fastened to the bedplate.

The operation of the mechanism thus far described may perhaps best beillustrated by a description of the complete cycle of events during thefeeding and packing of one increment of powdered metal. Starting from acondition in which the ram 25 is just beginning its upward or returnstroke, the parts will be in a position as shown in the solid lines ofFigure 3. When in this position, hydraulic pressure will be appliedthrough line 6| to chamber 64, and die piston 5| will be forced towardthe inner end of die cylinder 49. This hydraulic pressure will alsocause the die cylinder to be forced against nuts 11, thus creatingtension in bolts 89 and tending to move bearing plate 1| inwardly. Itwill thus be seen that the engagement of die piston 5| with retainingblock 43 and the engagement of bearing plate 1| with retaining block 44will force both of these blocks against their corresponding diesegments, thus locking the die segments in their closed position as seenin Fig. 8. This will increase the frictional resistance of thecompressed rod within the die to such a degree that it may not be forceddownwardly by the: action of ram 25. As the ram moves upwardly it willallow powder to ow from funnel I9 into the immovable entrance portion ofthe die which is surrounded by collar 45.

As the die again moves downwardly in its compression stroke, this powderwill be compressed within the immovable die portion so as to formanother increment of the compressed rod. During the iirst portion ofthis packing movement, the die segment portions within blocks 43 and 44will also remain immovable, thus maintaining the frictional resistancewhich prevents axial movement cf the rod. However, when a predeterminedaxial force has been reached, as reflected in the hydraulic pressurewithin the ram cylinder, the hydraulic pressure within chamber 64 willbe abruptly relieved, the means for accomplishing this action beingdescribed in detail below.

When the hydraulic pressurewithin chamber 64 is relieved, the inwardforces on clamping blocks 43 and 44 will be slackened, thus reducing thefrictional resistance of the powdered rod within the die segments. 1twill be understood of course that the actual movements of these parts isvery slight, the movement required being only that necessary to relievethe radial pressure on the rod. Since the axial force of the ram may nowovercome the frictional forces within the die, the rod will be moveddownwardly through the die until the ram again reaches the bottom of itsstroke. When this position is reached, the hydraulic pressure withinchamber 64 will again be built up to its previous degree, thus imposingthe frictional forces upon the rod which lock it against axial movement,and the cycle is repeated. It will be noted that during the releasingmovement of blocks 43 and 44, bearing plate 1|, bedplate 22 and diesegment supporting plates `4| and 42 all will move in substantial unisonwith retaining block 44, although the construction will permit suchrelative movement between block 44 and the bearing plate and bedplate asmay occur due to the reduction of internal stresses. On the other hand,die piston 5| and clamping block 43 move independently of the bedplateand the die segment supporting plates, the latter sliding upon the uppersurface of clamping block 43. The play in slot 39 will permit relativemovement between the supporting plates and the die segments.

The hydraulic system for controlling the events in the cycle ofoperation is shown schematically in Fig. 9, it being understood ofcourse that systems other than that shown in the illustrated embodimentcould be used. The ram cylinder 19 and the ram |2 are shown in the upperright hand portion of the diagram, and the die cylinder 49 and diepiston 5| are shown at the central right hand portion. In the diagram,solid lines are used to represent the main hydraulic conduits, anddotted lines are used for the pilot conduits. Pump motor 84 drives threehydraulic pumps 85, 86 and 81 which are designed to deliver hydraulicuid at various rates, the pumps being supplied from a tank 88. Pumpwhich is preferably of a variable delivery type, is used as the mainsupply pump for the ram cylinder 19, and is connected to a pressureregulating valve 89 by a conduit 9|, valve 89 being adjusted to delivera relatively high pressure, say 2,000 p. s. i. Valve 89 is connected toa filter 92 by a conduit 93, and the filter is connected to ram cylinder7 valve 94 by means of conduit .85.. A conduit $6 leads from port 94B.,this conduit hai/inge. branch 91 leading through a'r-estriction 98 .tothe lupper chamber 99 `of :the 'ram .cylinder by means of conduit .101|Conduit 96 :also .has :a :branch 102 nonnected through ram retardingvalve :|03 :and fa conduit |94 to "chamber .99. Valve 1I0-3 alwaysallows free flow .from port 1193A `to port 193B, but shuts orf now kfrom`I503B to 1113A when cam arm |65 vis depressed bycam 10B attached toram8|, this action occurring during an intermediate portion of the downstroke .Pump 8B is used as an auxiliary pump during the stroke andduring .the 'first portion of rthe lclown stroke, and for this purposeis connected to the supply fconduit s3 through pressure :regulating`valve 10.1., check valve |168 and conduit 1119. Valve |01 is set todeliver a relatively low pressure, vsay 500 p. s. i., .so that lcheckvalve .|08 will close `if a pressure .higher than this :exists in.supply .con-

duit 93.

.Pump -31 :is used to .supply .hydraulic pressure for the pilot vsystem(shown .in :dotted lines) through .a 'conduit if!! .a pressure:regulating valve I i2 set to deliver at an intermediate pressure, say.1,0% p. s. i. This pump .also supplies hydraulic .pressureto the vdiecylinder di) through a pressure reducing valve H3 set 'at .about 590 p.s.. i., die Vcylinder kvalve lill and .a conduit Bi. Pilot system`supply conduit il IE leads from `valve i l2, and has za branch 1|?!.leading to port IitSP of die cylinder pilot valve |I8 and another.'branch iis leading to `port I2|P `of ram ycylinder pilot valve 12|..Port :I lfSX is connected by control conduit |22 to conduit tied, avvariable setting relief valve 123 being inserted in conduit |22 andopening .only when the iluid Jin conduit IM has reached a predeterminedpres sure.

The .lower chamber 124 of the ram cylinder is connected by `conduit |215to port 94A, and this conduit is used both to supply `and to remove thefluid within chamber |124. A control conduit E2G connects conduit |25Vto port IIBY, so that the position of die cylinder pilot valve Hi8 iscontrolled by .the pressure differential between conduits Idd and F25.Pilot valve IIil in turn controls the position of .ram lcylinder Valve`Htl by means of conduits I2-7| and |28 leading to ports II-llX andllllY respectively., The pressure differential between .lines Idil and|25, or between the upper and lower ram cylinder chambers, thus ineiiect controls the movement of die piston I.

Ram .cylinder pilot valve 2| is connected by conduits |25 and |3| topor-ts 94X and "94Y1respectively, so that the position of ram cylindervalve ed is Vcontrolled by valve |2|, the latter thus acting as acycling valve. The *cycling valve is of -a rotary two-way type having aYlost motion connection to the ram |2 by `means of forked larms |32 and|33 and cam Y|131! attached to the ram. The arrangement .is vsuch thatvalve |2i will be moved from one position to another only at the top andthe bottom of I.the respective strokes. Valve Sd controls the supply ofhydraulio pressure to chambers .99 and |24 of the ram cylinder and itwill -th-us be seen that the position of the ram automatically .controlsthe direction in which it is driven.

The functioning of this automatic .hydraulic system may perhaps best beunderstood by a. description 'of the events which take place during acomplete cycle of operations. Starting Afrom an initial Ycondition inwhich the ram is at the eu-v treme upper end `oi :the stroke, as shownin Fig` .9, the manual :start and :stop `valve 135 may be moved to allow.flow of fluid from .pumps and .85 through conduits 93 Aand Hitrespectively to kconduit 95.. .A branch .line VI3i3 from `valve Y89 maytbe provided for the operation of the valve |93, so that Valves 89 and|91 .may be simultaneously opened. At the time of this initial movement,the `pilot .system `pump I! will VSupply iluid through conduits III, IISand :I I9 Ato ports I MP, HEP :and IZIP. With the ram cylinder ,pilotvalve :|21 in its position as shown .in Fig. 9, :port IlZIIA `will beconnected to port IZIP, and `port Il2fIB will be connected to ,port |2IT, that is, to tank. The .resultant pressure in conduit :I 29 over thatof conduit ISI will shift :ram lcylinder valve 94 to the right as 4shownin Fig. 9, 'connecting port 95A with pout 94T vand connecting a port 94Bto port 94E. Itwill `be understood, ofcourse, that the directions ofmovement `of the valves given in .this description :are merelyillustrative, and :that the actual .movements will depend upon theparticular valve port construction. Upon this .movement Iof valve 94.,.the supply from con-- duit Y95 will .flow into conduit 9S and throughthe branches si `and lez thereof to upper ram cylinder chamber 99. Thiswill cause a rapid downward initial movement of .ram I2, since the ram:cylinder is .bei-ng supplied by both pumps E15 fand 186. During thisaction, the pressure in Chamber '93 Vwill be greater Ythan that inchamber |24 and conduit 1M. However the pressure in cham-ber Sie is notgreat enough to open valve 4213 and this valve remaining closed, thepressure in control conduit |223 Will be greater than that in :conduitl11.22. Die cylinder vpilot valve IIB will thus -be held in its leftwardposition as shown in Fig. 9., :thus connecting lport l ISP to port HSAand connecting port IISB to tank. Conduit lf2? will therefore bepressurized, shifting die cylinder valve YIM so as to connect port l MPto port IIB. It will thus be seen that during the first portion of .the.-ram down stroke, pressure will vbe supplied .to the chamber of diecylinder 49, holding the dies in their locked position.

The ram will continue to move downwardly under the influence of thehydraulic .fluid delivered by pumps 85 and '85 until the compressiveforces in the ram are such that the pressure in the supply line I 69becomes greater than the setting of pressure regulator valve IG?. Whenthis occurs only the .iiuid from pum-p 85 will be delivered to thechamber 99 check valve |68 preventing .back lovv .of fluid to Ipump 85.r-Ihe rluid delivered from this .pump will be .returned to the tank viareturn .conduit |38. The ram will Acontinue to .move at the slower rateuntil cam engages arm 1.6.5, shutting off the flow from conduit |92 toconduit |94. The supply fluid from conduit Q5 will then .now onlythrough branch 97| and through restriction 9B to the chamber 99. The.restriction 93 will thus have the effect of .further reducing thevelocity of the ram as .it continues downwardly.

As the-charge .of powdered metal is compressed to greater density, theaxial forces in ram I2, and thus the hydraulic pressure `in chamber 99,will steadily increase. Valve |"23, which is .subject to the pressure inchamber S9, is vset to open when this pressure has reached a point atwhichthe proper density of the powder .charge is reached. This .pressurevmay be predetermined from tests or by calculation, and the valve `I2A3is preferably adjustable .so .that its opening pressure may be varied.Upon itsv opening, conduit |22, connected to port iliX, will besubjected to the pressure from chamber te. Conduit 12E, which isconnected between conduit IE and port HEY, is still subjected to therelatively low pressure in chamber |24. The resultant pressuredifferential will thus shift die cylinder pilot valve H8 to a positionsuch that port Hel is connected to port HSB and port HBA is connected totank. This in turn will shift die cylinder valve i I4, connecting port lIAB to tank. The die cylinder A9 will thus be abruptly relieved ofpressure, allowing the retraction of die piston 5i. As described above,this action will allow the rod to move downwardly under continued axialforce of ram l2. lt will be observed that since the supply fluid for theram nows only through restriction 98', the opening or valve 23 will notmaterially lessen the pressure in chamber 9s, so that there is no dangerof throwing in the auxiliary pump and thus speeding up the stroke. Therod will thus move downwardly at a controlled rate desirable for theoperation oi the furnace.

When the ram i2 reaches the bottom of its i stroke cam |34 will strikearm ls, shifting ram cylinder pilot valve l2! so thatport lZiP isconnected to port l2|B and port lziA is connected to tank. lThis actionwill shift ram cylinder valve 94 so as to connect port @4P to port 94Aand port 94B to tank. The pressure differential between chambers 99 and|24 will thus be reversed, and the fluid from pumps 85 and te will beginto drive the ram 8! upwardly. At the same time, the pressure drop inchamber @il will allow closing of valve 123, and the increased pressurein conduit 125 will cause pilot valve H8 to shift back to its originalposition, again shifting die cylinder valve H6 so as to apply pressureto the die cylinder. During the up stroke, the iluid from chamber Si!will flow freely through conduit HM and check valve E03 back to thetank. When the ram reaches the top of its stroke, cam 34 will strike armE32, shifting pilot valve IZI back to its original position which inturn will shift ram cylinder valve 94 so as to again supply pressure tocharnber S9, and the cycle will be repeated. It will be observed thatthe cycle is fully automatic and will repeat until start and stop valve35 is actuated to cut off the supply from pump d.

A die mechanism for compressing powders metal rods is thus provided inwhich a very high degree of consistency in the density oi the rod can beachieved. The releasing motion is accomplished during each stroke by afully automatic mechanism which is controlled solely by theinstantaneous axial force in the ram, the releasing point being easilyadjustable for different density requirements.

While it will be apparent that the preferred embodiment of the inventionherein disclosed is well calculated to fulfill the objects above stated,it will be appreciated that the invention is susceptible tomodification, variation and change without departing from the properscope or fair meaning of the subjoined claims.

What is claimed is:

l. A die for extruding a continuous rod of compressed powdered metal,said die including six elongated individual segments together forming ahexagonal passageway for the reception and formation of said rod, acollar securing said segments together in immovable relation at one endthereof, a pair oi' oppositely disposed clamping blocks extending alongthe remaining portion of said die, each of said clamping blocks beingmovable between a clamping position engageable with three of saidsections and a retracted position allowing radial expansion of saidsections; and means for moving said blocks between their clamping andretracted positions, said means comprising a hydraulic cylinder adjacentsaid die, a piston within said cylinder and movable between an extendedposition in operative engagement with ,one of said blocks and aretracted position out of such operative engagement, and connectingmeans between said cylinder and the other of said clamping blocks foroperatively engaging said other block when said first block is engagedby said piston, whereby both of said blocks are moved simultaneouslyinto their clamping position.

2. The combination according to claim l, means for supplying fluid underpressure to said cylinder to hold said clamping blocks in their clampingposition, and pressure actuated means controlled by the axial forceacting on said compressed rod for relieving said uid pressure when thatforce reaches a predetermined value.

3. A mechanism for extruding a rod of compresssed powdered metal,including a reciprocating ram for packing successive charges of saidpowder, a die for receiving and forming said charges, hydraulicallyoperated holding means for preventing axial movement of said rod by theaxial force of said ram, a holding valve for controlling the l'iow ofuid to said holding means, a ram cylinder and piston for actuating saidram, a ram cylinder valve for controlling the ilow of iluid to bothsidesJ of said ram piston and movable between a ram extending and a ramretracting position, a cycling valve controlled by the position of saidram to shift said ram cylinder valve between its said positions, saidholding valve being movable between a position in which it actuates saidholding means into clamping position and a position in which it allowsretraction of said holding means, and iluid pressure actuated means formoving said holding valve from its first-mentioned to itssecond-mentioned position in response to the attainment of apredetermined pressure acting on said ram cylinder in a direction toextend the ram.

4. A mechanism for extruding a continuous rod of compressed powderedmetal, including a die for receiving and forming incremental charges ofsaid powder, a ram movable between a retracted position away from Saiddie and an extended position within said die and compressing one of saidcharges, a ram cylinder and piston for operating said ram, holding meansengageable with said die for preventing axial movement of said rod whenthe ram is compressing one of said charges, a die piston and cylinderfor operating said holding means, a die cylinder valve for controllingthe ilow of fluid to said die cylinder, said die cylinder valve beingmovable between a clamping position in which said die piston andcylinder actuate said holding means and. a tripping position in whichsaid die piston and cylinder release said holding means, and means forcontrolling the position of said die cylinder valve, said meanscomprising valve actuating mechanism responsive to the pressure actingon the extending side of said ram cylinder for shifting said diecylinder valve to its tripping position when said pressure has reached apredetermined value.

5. Apparatus for forming a continuous rod of compressed powdered metalin successive increments, comprising, a die. having 'an openingtherethrough which normally is of substantially the same cross sec-tionthroughoutits length, means for supplying powdered metal` tothe dieopening at one end thereof, powder compressing means includingV areciprocating plunger operable to compress the powderwithi'n said; dieopening against the previously formed' portion ofT the rodl and thuscompact to iinal form successive increments of said rod in a portion ofthe. die openingadjacent said one end, the remaining portion of theylength ofsaid' die opening re` oei-ving a length of the fully' formedrod, at least a par-t of said remaining portion of the die be ingradially expansible, hydraulic pressure: op` erated mechanism forradially clamping the ex:- pansible portion of the die, means forsupplying operating uid to said mechanism at a pressure which will causethe mechanism to clamp, the die and hold the compressed' rod againstmovement in the die under the influence of, the force exerted by theplunger, and valve.. means actuated in response to theforce exerted bysaid plunger tocompress the powder for reducing. the pressure of' thefluid suppliedv to said clamping mechanism when the force exerted bysaid plunger reaches a predetermined value andY thus permit expansion ofthe split portion of the die and movement of` the compressed rod throughthe die opening after the plunger has completed only a portion of` itsstroke in the powder compressing direction.

6I. Apparatus for forming a continuous rod of. compressed powderedmetal. in successive increments, comprising a die having an openingtherethrough which normally is of substantially the same cross sectionthroughout its. length, means for supplying powdered metal to the dieopening at one end thereof, powder compressing means including aVreciprocating piunger operable to compress the powder With-in said dieopening against the previously formed portion of the rod' and thuscompact to` ina-l form successive increments or said rod in a portion oithe die opening adjacent. said one end, hydraulic; pressure means forreciprocating said plunger, the remaining portion ofthe length of saiddie opening receiving a. length of: the fully formed rod, atleast apartofsaid remaining portion of the die being radially expansible,hydraulic pres-V sure operated mechanism for radially clamping theexpansible portion of the die, means for supplying operatingfluid tosaidmechanism at a pressure which will cause the mechanism to clamp the dieand hold the compressed rod against movement in the die under the,Ainfluence of' the force' exertedv by the.V plunger,- and pressureoperated valve means.` actuated in response toh the pressure ofthehydraulic :duid acting on; said' plunger to compress the powder forreducing the pressure of the fluid supplied to said clamping mechanismwhen the. pressure of the hydraulicV uid' acting on said plunger reachesa predetermined value and thus permit expansion of the split portion ofthe die and movement of the compressed rod through the die opening afterthe plunger has completed only'A a portion of its stroke in the powdercompressing: direction.

EDGAR'-V K. LEAVENWORTH.

References Cited' in the flle of this patent UNITED STATES PATENTS'Number Name Date 473,579 Illingworth Apr; 26, 1892 757,409 Olson Apr.12, 1904 1,101,953- Bland June 23, 1914 2,097,502 Southgate Nov. 2, 19372,165,614 Cook et al June 1I, 1939 2,261,304 Sparks Nov. 4, 19412,284,704 Welblund et al. June 2, 1942. 2,289,787Y Kaschke et a1. July14, 1942 2,300,302 Morn Oct. 27, 1942 2,449,257 Tucker Sept. 14, 1948

